Fix local_filter_set() comment

It was wrong and misleading.
Provide proper comment for get_all_selected_files
Several code style updates for filelist.c
Rename filelist.c:get_all_selected_files()

To capture_target_files(), couldn't ever remember what it does because
of strange name.
Rename filelist.c:get_selected_files()

To capture_files_at(), which describes purpose of the function
much better.
Rename filelist.c:free_selected_file_array()

New name is free_file_capture().
Rename filelist.c:count_selected()

As recount_selected_files(), previous name wasn't that bad, but it
wasn't good either.
Fix wrong single file selection after =

Do not select single file to save selection.

Thanks to filterfalse.
Fix wrong number of selected files on status bar

Thanks to filterfalse.
Merge branch 'fix-local-filter-and-selection'

Fix wrong single file selection after applying local filter (also wrong
number of selected files on status bar).

Thanks to filterfalse.